1. Field of the Invention
This invention relates to a sheet member conveying device in a copying machine, a printer or the like.
2. Description of the Prior Art
A copying machine, a printer or the like is provided with a conveying device for conveying sheet members from a paper supply station to an image forming station or from the image forming station to a discharge port. This conveying device is variously designed to reduce jam, but it is impossible to eliminate jam completely. Thus, when jam has occurred, the jammed sheet member must be removed from the conveyance path, and how to make such jamming sheet member easy to remove is one task imposed on the sheet member conveying device. Usually, jam occurs at an intricate portion of the machine and it is difficult to remove a sheet member jammed at such portion and therefore, it has also been proposed that a sheet member obliquely moving which may jam be checked before it arrives at such portion and be stopped at a place where it is easier to remove the sheet member. Even in such case, the stopped paper must be removed by the operator.
The removal of the jammed paper or the paper stopped at the place where the removal is easier is carried out by withdrawing the sheet member conveying device out of the machine to provide a wide space which makes the removing work easier. In this case, the direction in which the sheet member conveying device is withdrawn out of the machine should preferably be the front side direction of the machine body. This is because, at the front side of the machine body, there is usually secured a space for the operator to carry out the copying or printing work and in contrast, it is often the case that the lateral or back side of the machine body is urged against a wall or the like to very much limit the working space.
Now, it is often the case that the direction of sheet member conveyance in the sheet member conveying device is orthogonal to the direction in which the sheet member conveying device is withdrawn toward the front side of the machine body. During said withdrawal, it is impractical to withdraw the entire sheet member conveyance path of the machine and therefore, it is the common practice to divide the sheet member conveyance path into several units and construct a unit-like sheet member conveying device so that any one of the units can be withdrawn as required.
Heretofore, when abnormal conveyance such as jam or oblique movement has been detected, the sheet member conveyance has been stopped on the spot to prevent any further spread of damage. When this is done, a sheet member sometimes stops astride adjacent two units. If both two units are withdrawn simultaneously at this time, there would be no problem, but if only one of the two units is withdrawn, since the direction of withdrawal is orthogonal to the direction of sheet member conveyance, the sheet member would be torn off and pieces of the sheet member would be scattered resulting in great inconvenience. The stopped condition of the sheet member is difficult to observe from outside of the machine and it is not known until the unit is withdrawn, and therefore the occurrence of such inconvenience is difficult to prevent.
Also, there are cases where jam or the like having occurred during continuous operation of the machine is followed by the start of conveyance of the next sheet member. If the entire machine is stopped at such time, the succeeding sheet member would stop in the conveyance path and, if such sheet member is left as it is, the portion of the sheet member which is urged against the conveyor roller would inveterately be curled. Therefore, if the machine is restarted without such sheet member being removed from the conveyance path, the sheet member would catch a guide or the like due to the curling habit thereof, thus causing a new jam. Accordingly, if the preceding sheet member has jammed, it is preferable to remove that preceding sheet member and also remove all the sheet members in the sheet member conveyance path. However, it is often the case with the operator that he pays attention only to the jammed sheet member and forgets the existence of the succeeding sheet members in the other conveyance units and fails to remove such succeeding sheet members.